Don't set SO_NOSIGPIPE when accepting sockets

This is inherited from the parent socket. Furthermore when attempting to
set it on a Unix socket domain it will result in an error.

Author: Thomasdezeeuw

src/socket.rs

@@ -285,7 +285,7 @@ impl Socket {
         )))]
         {
             let (socket, addr) = self.accept_raw()?;
-            let socket = set_common_flags(socket)?;
+            let socket = set_common_accept_flags(socket)?;
             // `set_common_flags` does not disable inheritance on Windows because `Socket::new`
             // unlike `accept` is able to create the socket with inheritance disabled.
             #[cfg(windows)]
@@ -762,8 +762,6 @@ const fn set_common_type(ty: Type) -> Type {
 }
 
 /// Set `FD_CLOEXEC` and `NOSIGPIPE` on the `socket` for platforms that need it.
-#[inline(always)]
-#[allow(clippy::unnecessary_wraps)]
 fn set_common_flags(socket: Socket) -> io::Result<Socket> {
     // On platforms that don't have `SOCK_CLOEXEC` use `FD_CLOEXEC`.
     #[cfg(all(
@@ -798,6 +796,34 @@ fn set_common_flags(socket: Socket) -> io::Result<Socket> {
     Ok(socket)
 }
 
+/// Set `FD_CLOEXEC` on the `socket` for platforms that need it.
+///
+/// Unlike `set_common_flags` we don't set `NOSIGPIPE` as that is inherited.
+/// Furthermore attempts to set it on a unix socket domain results in an error.
+fn set_common_accept_flags(socket: Socket) -> io::Result<Socket> {
+    // On platforms that don't have `SOCK_CLOEXEC` use `FD_CLOEXEC`.
+    #[cfg(all(
+        unix,
+        not(any(
+            target_os = "android",
+            target_os = "dragonfly",
+            target_os = "freebsd",
+            target_os = "fuchsia",
+            target_os = "hurd",
+            target_os = "illumos",
+            target_os = "linux",
+            target_os = "netbsd",
+            target_os = "openbsd",
+            target_os = "espidf",
+            target_os = "vita",
+            target_os = "cygwin",
+        ))
+    ))]
+    socket._set_cloexec(true)?;
+
+    Ok(socket)
+}
+
 /// A local interface specified by its index or an address assigned to it.
 ///
 /// `Index(0)` and `Address(Ipv4Addr::UNSPECIFIED)` are equivalent and indicate

tests/socket.rs

@@ -511,7 +511,7 @@ where
         panic!("unexpected error: {}", io::Error::last_os_error());
     }
     assert_eq!(length as usize, size_of::<libc::c_int>());
-    assert_eq!(flags, want as _, "non-blocking option");
+    assert_eq!(flags, want as _);
 }
 
 const DATA: &[u8] = b"hello world";
@@ -631,6 +631,30 @@ fn unix() {
     assert_eq!(&buf[..n], DATA);
 }
 
+#[test]
+fn unix_accept() {
+    if !unix_sockets_supported() {
+        return;
+    }
+    let mut path = env::temp_dir();
+    path.push("socket2");
+    let _ = fs::remove_dir_all(&path);
+    fs::create_dir_all(&path).unwrap();
+    path.push("unix_accept");
+
+    let listener = Socket::new(Domain::UNIX, Type::STREAM, None).unwrap();
+    listener.bind(&SockAddr::unix(&path).unwrap()).unwrap();
+    listener.listen(1).unwrap();
+
+    Socket::new(Domain::UNIX, Type::STREAM, None)
+        .unwrap()
+        .connect(&SockAddr::unix(path).unwrap())
+        .unwrap();
+
+    let (socket, _) = listener.accept().unwrap();
+    assert_common_flags(&socket, true);
+}
+
 #[test]
 #[cfg(all(feature = "all", any(target_os = "android", target_os = "linux")))]
 #[ignore = "using VSOCK family requires optional kernel support (works when enabled)"]